High velocity projectiles

ABSTRACT

A shaped charge and projectile combination for firing from a weapon, the combination including projectile ( 3 ), shaped charge ( 1 ) of high explosive material and metal liner ( 2 ) located between charge ( 1 ) and projectile ( 3 ). Charge ( 1 ) includes detonator ( 6 ) and cavity ( 4 ) in an external face facing the muzzle of the weapon, cavity ( 4 ) being shaped to axially concentrate explosive on detonation of charge ( 1 ) towards the rear ( 5 ) of projectile ( 3 ). Metal liner ( 2 ) forms a jet of liner material on detonation of charge ( 1 ) to impact the rear ( 5 ) of projectile ( 3 ) and so propel projectile ( 3 ) from the weapon at high velocity, typically greater than  1000  m/s and up to  6000  m/s. Projectile ( 3 ) therefore travels a flatter trajectory and has a higher penetrating power than a conventionally propelled projectile.

FIELD OF INVENTION

The invention relates to high velocity projectiles and in particular tocombinations of shaped charges and projectiles where detonation of theshaped charge causes a liner to deform and be accelerated providingkinetic energy to a projectile.

BACKGROUND

Guns typically use gas pressure within a barrel to propel a projectile.Examples include air rifles and armaments using low velocity explosivesuch as cordite or black powder that contributes to provide sufficientvolume and/or pressure of gas within the confines of a barrel to propela projectile such as a bullet or shell from the barrel of the gun. Forexample, cordite is a combustible rather than explosive material, suchthat the detonation of a primer will ignite the cordite to createsufficient gas pressure to propel the bullet. Guns are typicallyprovided with a rifled barrel to spin the bullet and assist in stabilityof the bullet along its flight path and hence accuracy of the bullet.Some guns do not use a rifled barrel, for example shot guns, where anumber of projectiles (shot) are propelled by combustion of explosivealong the barrel.

There have been many attempts to produce high speed projectiles.Examples include using longer gun barrels, using rockets or otherpropulsion means to aide the transfer of kinetic energy to theprojectile. Further examples also include linear motors and hydrogenguns both of which require long barrels. Long barrelled weapons are notsuitable in combat situations.

In military applications, tanks and other armoured vehicles have madeuse of new materials for armour making it more difficult to design gunsthat fire projectiles capable of penetrating the armour. Similarlyadvances in body armour have made it difficult for conventional bulletsto penetrate the armour and injure the wearer.

A shaped charge or metal lined cavity shaped charge is a metal linedhigh explosive charge with a mainly hemispherical or conical cavity.Upon detonation of the explosive of the shaped charge the detonationwave sweeps forward and begins to collapse the metal liner at its apex.The explosive force compresses and deforms the metal liner and producesa molten (or metal) jet moving at very high speed. This jet reachesspeeds in excess of 4 to 12 km/s. The production of the metal jet istermed the ‘Munroe effect’. Shaped charges of this type produce a metaljet that is a useful penetrating and perforating device.

However, one problem with shaped charges is that the effective range ofthe molten jet is very limited. Due to the nature of detonation and thedesign of the shaped charge liner the production of the molten jet isnot consistent. The jet also has a large variation in mass and velocityover its length and breaks up after travelling a short distance.

Due to the large gradient in mass and velocity, detonation of the shapedcharge must occur a specific distance from the target for the jet toobtain the greatest speed possible before it begins to perforate thetarget. If the charge is detonated too far from the target the ejectedliner material will have broken up into small pieces before reaching thetarget and the speed of the jet will have slowed. If the shaped chargeis detonated too close to the target the jet may not have reached idealspeed and performance may be reduced.

SUMMARY OF INVENTION

In broad terms in one aspect the invention comprises a shaped charge andprojectile combination including a projectile, a shaped charge of highexplosive material including a cavity in an external face of the charge,shaped to axially concentrate explosive upon detonation of the shapedcharge towards the projectile, and a metal liner between the shapedcharge and the projectile, to form a jet of liner material on detonationof the shaped charge to impact the rear of and propel the projectile.

The shaped charge and projectile may be combined into a cartridge.

In broad terms in a further aspect the invention comprises a shapedcharge and projectile in combination including a projectile, a body of ahigh explosive material forming a charge and including an internalcavity open to one end of the charge to axially concentrate explosiveforce upon detonation of the shaped charge towards the rear face of theprojectile, and a metal layer lining the interior of the cavity in theshaped charge.

In broad terms in a further aspect the invention comprises a method ofpropelling a projectile including providing a projectile, providing ashaped charge of high explosive material including a cavity in anexternal face of the charge, the cavity shaped to axially concentrateexplosive upon detonation of the shaped charge towards the projectileand a metal liner between the shaped charge and the projectile,detonating the shaped charge at an end opposite the cavity to form a jetof liner material, and focus the jet on the rear of the projectile sothat at least a portion of the kinetic energy of the jet is transferredto the projectile to propel the projectile.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be further described with reference to theaccompanying figures, by way of example and without intending to belimiting, wherein:

FIG. 1 shows an example combination shaped charge and projectile;

FIG. 2 shows a shaped charge and liner;

FIG. 3 shows the results of a simulation showing a jet of moltenmaterial being formed from a liner;

FIG. 4 shows the results of a simulation showing a jet of moltenmaterial formed from a liner providing kinetic energy to a projectile;

FIG. 5A shows a projectile and shaped charge with liner beforedetonation;

FIG. 5B shows a simulation of the shaped charge, liner and projectileafter detonation of the explosive of the shaped charge;

FIG. 5C shows a simulation of the shaped charge, liner and projectileafter detonation as the liner forms a jet.

FIG. 5D shows a simulation of the liner and projectile after detonationof the shaped charge.

FIG. 6 shows a combination shaped charge and projectile including aballistic disk; and

FIG. 7 shows a projectile with a jet trap.

DETAILED DESCRIPTION

FIG. 1 shows an example of the combination of shaped charge andprojectile of the invention. The shaped charge 1 has a substantiallycylindrical or frusto conical outer shape of high explosive with acavity 4 facing the open end of a firing weapon. The boundary betweencavity 4 and the high explosive 1 is provided with metal liner 2. Housedinside cavity 4 is projectile 3. The high explosive of the shaped chargeis also provided with detonation means 6.

When the explosive is detonated the liner forms into a jet of moltenmaterial that impacts the rear of the projectile. At least a portion ofthe kinetic energy of the liner is passed to the projectile and propelsthe projectile. Because the projectile is a free moving object theimpact of the jet on the projectile propels both the projectile and jetalong the original axis of movement of the jet. Ideally this axis ofmovement of the jet is the central axis of the barrel of the firingweapon. The axis is also ideally coaxial to the central axis of theprojectile.

The explosive used in the shaped charges is high explosive. By highexplosive is meant an explosive material with a detonation velocity inexcess of 1000 m/s. Examples of the high explosives include Semtex, TNT,RDX and PETN.

The explosive charge and liner are shaped such that on detonation of theexplosive charge the liner forms a jet of molten material coaxial withthe centre axis of the projectile. The back of the projectile 5 isformed from a material able to withstand the high temperatures and forceof the jet. Suitable materials include, but are not limited to, carbon,titanium, tungsten, ceramics, steel, uranium and depleted uranium. Insome cases the rear of the projectile 5 may include an aperture toincrease the surface area of the rear of the projectile and the area onwhich the jet will impact.

The combination of shaped charge and projectile shown in FIG. 1 issuitable for fixed diameter weapons including barrelled weapons. In thecombination shown in FIG. 1 the projectile has smaller calibre than thecharge and will not be in close contact with the inside of the barrel ofthe weapon. In combinations such as that of FIG. 1 the barrel of theweapon will therefore not require rifling although these combinationsare suitable for use in weapons with rifled barrels. In combinationssuch as that of FIG. 1 the projectile may be provided with stabilisingmeans such as fins to provide stability to the flight path of theprojectile once it has exited the weapon.

In other combinations the projectile may be of the same or greatercalibre than the shaped charge. In these systems if the projectile issame calibre as the weapon and the barrel of the weapon is provided withrifling the projectile may be designed to interact with the rifling andthus provide spin and stability to the projectile.

The combination of shaped charge and projectile allows the projectile tobe propelled at high velocity, typically greater than 1000 m/s. Theprecise speed of the projectile will depend on many things including thehigh explosive chosen for the shaped charge, the relative sizes of theshaped charge and projectile, the geometry of the explosive (i.e. theprecise shape of the shaped charge), the point of detonation, the massand geometry of the metal liner, the distance between the liner and theprojectile, the way the detonated explosive decomposes, the material ofthe liner, and the weight, size and material of the projectile.

The use of high explosive provides more propelling force than a lowexplosive. Different types of high explosive provide differentpropelling forces. A larger shaped charge containing high explosive willprovide more explosive force than a smaller shaped charge containing thesame high explosive.

The geometry of the shaped charge also has an effect on the propellingpower of the jet on the projectile. A shaped charge with a cylindricalcavity produces a jet that is a function of the length of the cylinder.For a shaped charge with a cylindrical cavity varying the amount ofexplosive and liner along the cavity can vary the jet production. In thecase of a shaped charge with a cylindrical cavity the liner the cylinderthe greater the length of jet produced. In a shaped cue with a conicalor hemispherical cavity and liner the length of the jet increases as afunction of the diameter of the charge. In a shaped charge with aconical cavity the angle between the liner and the central axis of thecharge also affects the jet formed. The smaller the angle the faster thespeed of the jet formed.

The larger the shaped charge is in relation to the size of theprojectile the larger the force provided to the jet will be in relationto the projectile and the more kinetic energy will be imparted to theprojectile.

As described above the geometry of the metal liner affects the jet. Theliner has the same shape as the outer boundary of the shaped charge. Forexample a cylindrical liner will form a jet the length of which dependson the length of the cylinder. The mass of the liner material alsoaffects the density and speed of the jet.

The distance between the liner and the projectile also affects theperformance of the projectile. If the projectile is too close to theliner the projectile may be consumed or deformed by the jet. If theprojectile is too far from the liner the jet formed from the liner mayhave lost kinetic energy or start to break up before providing kineticenergy to the projectile.

Performance of the projectile is also affected by the dimensions of theprojectile. Ideally the projectile is light, strong and has temperatureresistant material covering at least the rear of the projectile. In someembodiments the projectile may be completely covered with a layer oftemperature resistant material. As stated previously suitable materialsinclude, but are not limited to, carbon, titanium, tungsten, ceramics,steel, uranium and depleted uranium.

FIG. 2 shows a shaped charge and liner that may be used in combinationwith a projectile. The shaped charge includes an outer casing, centralarea of high explosive and a cavity that is lined with a liner. Asdescribed above the shape of the cavity and liner affects the formationof the Jet of molten material from the liner.

When the shaped charge is detonated a high temperature high intensityjet will be focused on the rear of the projectile with a detonationvelocity in excess of 1000 m/s and typically of the order of 5000-6000m/s depending of the explosive material chosen for use in the shapedcharge. The high explosive of the shaped charge may be Semtex or othersuitable high explosive material.

Any suitable detonator may be used to detonate the high explosive of theshaped charge. For example, the shaped charge may be detonated byphysical impact by means of a firing pin or by means of electricaldetonation. Electrical detonation has the advantage of precise timing ofignition, rapid ignition and it prevents instability that might occurthough the physical movement of a firing pin. The high explosive of theshaped charge may also be detonated by laser detonation. Laserdetonation has the same advantages as electrical detonation. Electricaland laser detonation also enables the combination shaped charge andprojectile of the invention to be used with guns that have a safelymechanism where the gun will not fire unless an appropriate electricaldevice (such as an identity card) is in close proximity to the gun.Alternatively biometrics, such as fingerprint or facial recognition maybe used as a safety mechanism.

By using a shaped charge, and by transferring as much as possible of thekinetic energy of the jet of molten material into the kinetic energy ofthe projectile it is possible to cause the projectile to travel athigher velocities than conventional bullets. By increasing the velocityof the projectile, for example a bullet, to 1000 m/s or more the bulletcan travel in a much flatter trajectory that normal, have a much shortertine between the launcher and the target, and have a much higher impactvelocity allowing the bullet to penetrate a range of different armours.The projectiles of the combination projectile and shaped charge of theinvention have higher kinetic energy than conventional projectiles andcan therefore create more damage on impact. This in turn means that theprojectile is more effective over a greater distance than a conventionalbullet or shell. It also enables guns to be redesigned to have a muchgreater range and killing power for a lighter gun than conventionalguns.

Although the projectile describe here has been referred to as a bulletthe projectile for use with a shaped charge in the combination of theinvention is not limited to bullets. The projectiles may be shells,missiles or any projectile designed to be propelled from a weapon bydetonation of an explosive charge. In cases where the projectile istravelling long distances or includes a guidance system the projectilemay be provided with rockets for stabilisation and/or to provide furtherpropulsion.

Projectiles used as part of the invention may require stabilisationmeans. If the projectile has the same calibre as the internal diameterof the barrel of the weapon used to fire the projectile, the projectilemay include means to interact with any rifling in the barrel. In otherembodiments, such as those shown in FIGS. 1 and 5A to 5D where theprojectile is smaller than the internal diameter of the barrel, theprojectile may be provided with fins or other stabilising means, thatmay stabilise the projectile with or without spinning the projectile.Projectile of the same calibre as the barrel of the weapon from whichthey are fired (as well as those with smaller calibre than the barrel)may be provided with stabilisation means such as dimples, grooves orother indentations. The stabilisation means may be arranged to smooththe path of the projectile over its trajectory or provide stability byspinning the projectile. Combinations of the abovementionedstabilisation means may be used.

FIG. 3 is a computer simulation of the jet produced from the shapedcharge of FIG. 2. This Figure shows the jet of deformed liner materialapproximately 14.5×10⁻⁶ seconds after detonation of the high explosiveshaped charge. The key at the right hand side of the figure shows thevelocity gradient of the jet. In this figure and subsequent figures thedirection of movement of the jet is from left to right. As can be seenfrom this figure the velocity of the jet is greatest at the right handside of the jet indicating that the front of the jet is moving morequickly than the rear of the jet. The jet continues to lengthen furtherand the front of the jet continues to have greater velocity than therear of the jet. Eventually the jet breaks into at least two pieces, afaster moving front piece and a slower moving rear piece.

FIG. 4 is a computer simulation showing a jet and a projectileapproximately 14×10⁻⁶ seconds after detonation at the high explosiveshaped charge. As with FIG. 3 the key at the right hand side of theFigure shows the velocity gradient of the jet. As can be seen from thefigure the jet is providing kinetic energy to the projectile and theprojectile has greater velocity than the jet. Further firing images areshown in FIGS. 5A to 5D.

FIGS. 5A to 5D show a computer simulation of the detonation of acombination shaped charge and projectile of the invention. FIG. 5A showsthe arrangement of the shaped charge and projectile 50 beforedetonation. In this example the projectile is conical with height of 2mm and base of 2 mm. The outer diameter of the shaped charge is 25.4 mm.The shaped charge has a conical cavity and liner 51 is provided at theboundary between is explosive of the shaped charge and the cavity.

FIG. 5B shows a moment approximately 5×10⁻⁶ seconds after detonation ofthe explosive of the shaped charge. Jet 51 is forming behind projectile50 and kinetic energy from the explosion is being passed to projectile50. FIG. 5C shows further formation of the jet approximately 12×10⁻⁶seconds after detonation. Projectile 50 remains at the front end of thejet.

Finally FIG. 5D shows further formation of jet 51 and the projectile 50approximately 16×10⁻⁶ seconds after detonation. Comparing FIGS. 5C and5D it can be seen that the length of the jet is increasing. It can alsobeen seen that the projectile is further away from the front of the jetin FIG. 5D than in FIG. 5C. This shows that the projectile has greatervelocity than the jet and will therefore have a greater range than thejet. It should be noted that none of FIG. 5A to 5D include velocityprofiles for either the jet of liner material. Typical velocity profilesfor the jet and projectile are shown in FIGS. 3 and 4.

In some embodiments the liner may be replaced by a ballistic disk asshown in FIG. 6. Ballistic disks in a ballistic disk/shaped chargecombination have previously been used as penetrating and perforatingdevices. Ballistic disks can be formed into projectiles by thedetonation of the shaped charge. In the embodiment shown in FIG. 6 whenthe shaped charge is detonated the ballistic disk impacts on the rear ofthe projectile and provides kinetic energy to the projectile.

In FIG. 6 a ballistic disk is used to propel the projectile. In thiscase, the detonation of the shaped charge causes the charge to shoot outa ballistic disk. This ballistic disk in turn impacts the rear end ofthe projectile which is provided with a heat resistant material, andmore preferably a highly dense material (such as depleted uranium) atthe rear of the preformed projectile. Because the projectile is a freemoving object, the collision with the ballistic disk moves both theprojectile and the disk along the original axis of movement of theballistic disk.

FIG. 7 shows a projectile with a jet trap (see below) and an oversizedshaped charge. By using a projectile which is a fraction of the mass ofthe metal liner of the shaped charge, more of the kinetic energy fromthe detonation can be transferred to the projectile to enable theprojectile to reach hyper-velocity speeds in excess of 6,000 metres persecond.

In one embodiment the jet trap is a frusto-conical aperture with itslargest diameter at the rear of the projectile. The surrounding materialis preferably formed of a heat resistant high-density material such asdepleted uranium. The jet trap is designed as a means of transferringthe kinetic energy of the resulting jet resulting from the detonation ofthe shaped charge. By increasing the surface area at the rear of theprojectile, which interacts with a jet, it is possible to prolong theimpact time and increase the surface area of interaction between the jetand the projectile. At its simplest, a jet trap is simply a conical orfrusto-conical indent in the rear of the projectile.

Preferably a diameter of the mouth of the jet trap is marginally greaterin size than the diameter of the jet produced by the detonation of theshaped charge at the point where it first interacts with a projectile.

The surface area of the interior of the jet trap may be increased bysuitably shaping the internal surface of that jet trap. In oneembodiment the surface area can be increased by forming a type of starindent to thereby increase the jet trap surface area.

By appropriately shaping the interior of the jet trap it is possible tocreate the effect of rifling, and hence spinning of the projectile.

Preferably the inner surface of the jet trap can be aligned so that whenimpact occurs with a jet from the detonation of the shaped charge, thejet touches a surfaces that imposes a centrifugal effect on theprojectile.

Because of the rate of transfer of kinetic energy to the projectile, itis possible to design artillery pieces that can be much smaller thanconventional artillery, and yet achieve the same killing power or samerange as a much larger conventional gun. In addition, greater distancescan be achieved as a result of grater speed. This also results in aflatter trajectory and thus it will be possible to use the high velocitybullet concept to provide a cheap alternative to missiles or rockets,whilst covering the same range or impact velocity. It may also bepossible to make use of this invention to assist in the launch ofunmanned satellites, or probes into the upper atmosphere provided theyare capable of withstanding the substantial g-fores associated with thelaunch velocity. In such cases, a projectile containing a rocket ormultiple shaped charges would be launched at high velocity and thenaccelerated to escape velocity by use of a rocket or other propulsionmeans.

The foregoing describes the invention including preferred forms thereof.Alterations and modifications as will be obvious to those skilled in theart are intended to be incorporated within the scope hereof as definedby the accompanying claims.

1. A shaped charge and projectile combination including: a projectile ashaped charge of high explosive material including a cavity in anexternal face of the charge, shaped to axially concentrate explosiveupon detonation of the shaped charge towards the projectile, and a metalliner between the shaped charge and the projectile, to form a jet ofliner material on detonation of the shaped charge to impact the rear ofand propel the projectile.
 2. A shaped charge and projectile combinationas claimed in claim 1 wherein the shaped charge is housed in a casingforming a cartridge.
 3. A shaped charge and projectile combination asclaimed in claim 2 wherein the projectile is retained within the cavityin the shaped charge.
 4. A shaped charge and projectile combination asclaimed in any one of claims 1 to 3 wherein the projectile has aballistic shape with a front end and a rear end and wherein at least therear end includes a layer of temperature resistant material.
 5. A shapedcharge and projectile combination as claimed in claim 4 wherein thetemperature resistant material is one of the group of carbon, titanium,tungsten, ceramics, steel, uranium or depleted uranium.
 6. A shapedcharge and projectile combination as claimed in any one of claims 1 to 5wherein the projectile includes an aperture facing the liner of theshaped charge.
 7. A shape charge and projectile combination as claimedin any one of claims 1 to 6 wherein the projectile includesstabilisation means.
 8. A shaped charge and projectile in combination asclaimed in claim 7 wherein the stabilisation means includes externalwings or fins.
 9. A shaped charge and projectile in combination asclaimed in claim 7 wherein the stabilisation means includes dimples orgrooves.
 10. A shaped charge and projectile in combination as claimed inclaim 7 wherein the stabilisation means includes means to interact withrifling on the inside of a barrel of a weapon.
 11. A shaped charge andprojectile combination as claimed in any one of claims 1 to 10 whereinthe projectile is a bullet.
 12. A shaped charge and projectilecombination as claimed in any one of claims 1 to 10 wherein theprojectile is a shell.
 13. A shaped charge and projectile combination asclaimed in any one of claims 1 to 12 wherein the cavity in the shapedcharge has a concave shape.
 14. A shaped charge and projectilecombination as claimed in any one of claims 1 to 12 wherein the cavityin the shaped charge has an ovaloid shape.
 15. A shaped charge andprojectile combination as claimed in any one of claims 1 to 12 whereinthe cavity in the shaped charge has a cylindrical shape.
 16. A shapedcharge and projectile combination as claimed in any one of claims 1 to15 wherein the explosive of the shaped charge is arranged to bedetonated by electrical ignition.
 17. A shaped charge and projectile incombination as claimed in any one of claims 1 to 15 wherein theexplosive of the shaped charge is arranged to be detonated by a firingpin.
 18. A shaped charge and projectile in combination as claimed in anyone of claims 1 to 15 wherein the explosive of the shaped charge isarranged to be detonated by laser ignition.
 19. A shaped charge andprojectile in combination as claimed in any one of the preceding claimswherein the projectile has a diameter which is less than the widestcross-section of the cavity in the shaped charge.
 20. A shaped chargeand projectile in combination as claimed in any one of the precedingclaims wherein the liner is a ballistic disk.
 21. A shaped charge andprojectile in combination including: a projectile, a body of a highexplosive material forming a charge and including an internal cavityopen to one end of the charge to axially concentrate explosive forceupon detonation of the shaped charge towards the rear face of theprojectile, and a metal layer lining the interior of the cavity in theshaped charge.
 22. A shaped charge and projectile combination as claimedin claim 21 wherein the shaped charge is housed in a casing forming acartridge.
 23. A shaped charge and projectile combination as claimed inclaim 22 wherein the projectile is retained within the cavity in theshaped charge.
 24. A shaped charge and projectile combination as claimedin any one of claims 21 to 23 wherein the projectile has a ballisticshape with a front end and a rear end and wherein at least the rear endincludes a layer of temperature resistant material.
 25. A shaped chargeand projectile combination as claimed in claim 24 wherein thetemperature resistant material is one of the group of carbon, titanium,tungsten, ceramics, steel, uranium or depleted uranium.
 26. A shapedcharge and projectile combination as claimed in any one of claims 21 to25 wherein the projectile includes an aperture facing the liner of theshaped charge.
 27. A shaped charge and projectile combination as claimedin any one of claims 21 to 26 wherein the projectile includesstabilisation means.
 28. A shaped charge and projectile in combinationas claimed in claim 27 wherein the stabilisation means includes externalwings or fins.
 29. A shaped charge and projectile in combination asclaimed in claim 27 wherein the stabilisation means includes dimples orgrooves.
 30. A shaped charge and projectile in combination as claimed inclaim 27 wherein the stabilisation means includes means to interact withrifling on the inside of a barrel of a weapon.
 31. A shaped charge andprojectile combination as claimed in any one of claims 21 to 30 whereinthe projectile is a bullet.
 32. A shaped charge and projectilecombination as claimed in any one of claims 21 to 30 wherein theprojectile is a shell.
 33. A ed charge and projectile combination asclaimed in any one of claims 21 to 32 wherein the cavity in the shapedcharge has a concave shape.
 34. A shaped charge and projectilecombination as claimed in any one of claims 21 to 32 wherein the cavityin the shaped charge has an ovaloid shape.
 35. A shaped charge andprojectile combination as claimed in any one of claims 21 to 32 whereinthe cavity in the shaped charge has a cylindrical shape.
 36. A shapedcharge and projectile combination as claimed in any one of claims 21 to35 wherein the explosive of the shaped charge is arranged to bedetonated by electrical ignition.
 37. A shaped charge and projectile incombination as claimed in any one of claims 21 to 35 wherein theexplosive of the shaped charge is arranged to be detonated by a firingpin.
 38. A shaped charge and projectile in combination as claimed in anyone of claims 21 to 35 wherein the explosive of the shaped charge isarranged to be detonated by laser ignition.
 39. A shaped charge andprojectile in combination as claimed in any one of claims 21 to 38wherein the projectile has a diameter which is less than the widestcross-section of the cavity in the shaped charge.
 40. A shaped chargeand projectile in combination as claimed in any one of claims 21 to 39wherein the liner is a ballistic disk.
 41. A method of propelling aprojectile including: providing a projectile, providing a shaped chargeof high explosive material including a cavity in an external face of thecharge, the cavity shaped to axially concentrate explosive upondetonation of the shaped charge towards the projectile, providing ametal liner between the shaped charge and the projectile, and detonatingthe shaped charge at an end opposite the cavity to form a jet of linermaterial, and focus the jet on the rear of the projectile so that atleast a portion of the kinetic energy of the jet is transferred to theprojectile to propel the projectile.